Electric-motor control.



Nn. '645,ns.

F. A. MERmcK..

ELECTRIC MOTOR CUNTROL.

(Application lad Apr. 19, 1899.)

Patenled Mar, I3, '1900.

M, grsst-s: i I y @WW Urirrni) STATES PATENT Carica.

FRANK A. MERR-ICK, OF JOHNSTOWN, PENNSYLVANIA, ASSIGNOR TO TII JOHNSON COMPANY, OF PENNSYLVANIA.

ELECTRIC-MOTOR CONTROL.V

sPEcIFIoATIoN forming pari; of Letters Patent No. 645,116, dated Meren 13, 19oo. ippiieenen nea Apni 19, 1899. sena No. 713.690. die modus To @ZZ whom it may concern.-

Be it known that I, FRANK A. MERRICK, of lIohnstown, in the county of Cambria and State of Pennsylvania, have invented a new andfuseful Improvement in Electric-Motor Control, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, which form part of this specification.

Io This invention has relation to a system of control for electric motors, and has for its object generally the provision of a method of accelerating and regulating a plurality of motors by a series of gradual changes effected I5 in the motor-circuit, whereby its resistance is decreased and the strength of the fields is varied in proportion to the increase in coun ter electromotive force.

The invention is especially designed for opzo eration in connection with electric-railway motors, but may be used for other purposes.

Generally described the invention consists in a method of control wherein the motors are started in a position of maximum resistz5 ance, being in series as a whole, and are gradually shifted to a position of least resistance or in parallel as a whole by intermediate changes in the circuit connections, whereby the field-windings are first connected in parallel with the armatures still in series and subsequently the armature windings are coupled in parallel with the field-windings in series.

The invention, may also involve the use of further changes intermediate those enumerated, whereby the condition of the circuit is more gradually changed, and it may also involve the use of artificial resistance to alimited extent, as at starting.

4o The invention further consists in certain combinations of steps, which will be hereinafter described, and pointed out in the ap pended claims.

Referring to the accompanying drawings,

Figure l is a diagrammatic views howing two electric motors, a controller, a reversing and cut-out switch, and such parts of the wiring and connections as are necessari,T to illustrate the nature and operation of my invention.

Fig. 2 is a similar view showing a modied form of controller. Fig. 3 shows the successive circuit connections made by themovement of the controlling-switch shown in FigT 1. Positions Nos. 1, 2, 3, 4, 7, 10, and 12 of this figure also represent the successive cir- 5 5 cuit changes made by the controller shown in Fig. 2.

In the figures, A' A2 represent the armatures of the motors, and F F2 the field-coils. l

Squares 1 to 12 represent a series of iixed 6o contact-brushes which form part of the controlling-switch and which are arranged toengage with a series of movable contacts, (designated by c to 026.) These contacts may consist of contact-pieces secured to arotar'y cylin- 65 drie drum operated by a suitable hand-lever. Controller-switches of the same type of Inechanical construction are well known in the art, and it is sufficient to show and describe the arrangementof the movable contacts, These 7o contacts are divided into five groups, each of which is electrically disconnected from the other groups, but has all its individual contacts electrically connected. Contacts 'c' to c7, inclusive, constitute'one group; contacts 75 c8 c9010 constitute a second group; contacts c11 to c, inclusive, a third group; contacts 018` to o23, inclusive, a fourth group, and contacts c25 and c26 a iifth group. A further single contacto24 is connected to ground through 8o the shaft of the controller.

It will be noted that certain. of the contacts While belonging electrically to one group With respect to position are within the lines of another group, so that certain of the brushes may engage with contacts of two adjacent electrical groups. Brushes 6, 7, 8, 9, and l1 are of this class. Certain ofthe contacts are also arranged to be bridged by the brushes in certain positions. The purpose of this de- 9o scribed relationof the contacts will be better understood after the different posit-ions of the controlling-switch have been examined.

B represents the coil of an electromagnetic arc interrupter or blow-out through-which the current passes to the controller and motor circuit and which is connected to the y brush 1.

R represents an artificial resistance which I prefer to insert in circuit when the motors are iirst started and which is connected between brushes 2 and 5 and also with brushes IOO tacts c2 c4 c5, the resistance at the last position t and i2.

Z designates a group of moving contacts which form part of a combined reversing and cut-out switch, and squares 13 to 22 indicate the contact-brushes which coperate with such contacts. This switch forms no part of the present invention further than it is necessary to employ some switch of this character, and it need not, therefore, be described indetail. For the purpose of tracing out the circuits hereinafter it will be assumed that the brushes 13 to 22 are in engagement with those contacts Z which are on the vertical line ZiL and which are further designated as Z Z2, &c., to Z2, respectively. Brush 13 is connected to brush 6 of the controller by conductor C2. The field-coils F2 are connected between the brushes 14 and 16. Brush 15 is connected to brush 1S by a conductor C2. Brush 17 is connected to brush 9 by conductor C4. Brush 18 is connected to brush 5 by conductor C5. Field F is connected between brushes 19 and 20. Brush 21 is connected to brush 7 by conductor C, and brush 22 is connected to brush 11 by conductor C7.

At the first position of the switch brushes 1, 2, 6, 7, 8, 9, 10, 11, and 12 are respectively engaged with the contacts c c2 010 c14 c15 c20 c22 c25 C2G and the course of the current (assuming that the brushes 13 to 22 are in the position Z2, as above stated) is as follows: from the trolley, through blowout coil B, to brush 1,contacts c/ c2, brush 2, resistance R, brush 5, connect-ion C5, brush 18, Contact Z5, contact Z2, to brush 20, through field-windings F' to brush 19, to contact ZG, to contact Z2, brush 21, connection C, to brush 7, contacts c14 C15, brush 8, through armature A', brush 11, contacts c25 026, brush 12, through connection C to brush 6, through conductor C2 tobrush 13, to contacts Z' Z2, to brush 1G, through field F2 to brush 14, to contacts Z2 Z, brush 17, connection C4, brush9, contacts 022 022,v to brush 10, through armature A2 to ground G. It Will be seen,therefore,that in this position the current flows through the blow-out coil, the artificial resistance, and the armatures and fields in series, so that the motor-circuit presents a maximum resistance. In the next three positions the only change made in the circuit is to gradually cut outthe resistance R as brushes 3, 4, and 5 are respectively engaged with the respective con- (No. 4) being entirely cut out of circuit. I prefer to employ these preliminary steps, wherein the resistance is gradually removed from the circuit as the counter electromotive force of the motors gradually increases, but they may be dispensed with, not, however, without the disadvantage of a considerable inrush of current at the start. In the fifth p0- sition the brush Gis bridging onto the contact c2 of the first group and the brushes 7 and S still engage the contacts C14 C15, the result being that the current divides, one part passing by brush 5 through the motors in series as before and the other part by brush 6, conductor C2, brush 13, contacts Z Z2, to brush 16, so that a shunt is thrown around one motor and the volume of current passing through the motor-circuit is considerably increased. The position 5a (illustrated in Fig. 3) is a momentary position only, in which the circuit through the first motor is broken by the brushes 7 and 8 leaving the contacts c1'L and cliin passing to position G. In this latter position the circuit through the field of the first motor remains open, but its armature is connected in shunt with the circuit by reason of the brush 9 bridging over onto the contact 017 of the third group and the brush 11 engaging the Contact C22 of the fourth group, whereby the current after passing through F2 divides, one part going by brush 9, contacts c1`7 o16, brush 8, through armature A', brush 11, contacts 022 022, brush 10, through armature A2 to ground, and the other part going direct to brush 10 and armature A2 to ground. In passing from position 6 to position 7 the brush 9 entirely leaves contact 020, thereby breaking the short circuit around armature A and sending the current in series through the two armatures With the second eld also in series therewith, the circuit through field F remaining open by reason of the fact that brush 7 is not engaged with any contact. This is the position or circuit relation denoted by 6H. Positions 5, 5, 6, and 62 are temporary or passover positions and are passed over rapidly preparatory to establishing the connections shown by position No. 7 and effect a gradual decrease of circuit resistance. In position No. 7 brush 7 again becomes engaged with a contact (cl2) of the third group, and thereby restablislies the circuit through the first field. A portion of the current, however, passes from contact c7 to brush 6 and conductor C2 to and through the second field.

IOO

IIO

The two currents meet in the contacts of the third group and pass through the two armatures in seriesY to ground. lt will be seen, therefore, that the two fields are' in parallel with the two armatures in series, resulting in a decrease in the strength of the fields and an increased flow of current. In passing from position 7 to position 8 the brush 6 leaves the contact c7, and thereby cuts the field F2 out of circuit, the entire current passing by brush 5 through the field F and armatures A' A2 in series by the course heretofore traced. This gives the condition of the circuit shown at 7. In position 8 the connections remain substantially as hefore,except that the brush 11 comes in contact with the Contact C22, and thus establishes a shunt to ground around the armature A2 through the shaft of the controller. In passing from position 8 to position 9 thc brush 11 leaves the contact 022 entirely, and thereby cuts armature A2 out of circuit. But

one motor is now in circuit. When position 9 is reached, the brush 7 is bridging the contacts e9 cl3, so that after the current has passed through the first eld it divides, one path being from contact C8, brush 6, dac., through the second field to the third group of contacts and thence through A, brush 11, contact 024 to ground, and the other path being a short circuit around the second field by way of brush Sto A', dre., (the brushes Sand 9 bridging over onto the contacts c16 and 012 of the fourth group.) Passingfrom position 9,brusl1 7 leaves the contact cl2, thereby cutting out the shunt around the second field. The circuit is now in the condition shown at Qa-that is to say, fields F F2 are connected in series with armature A and armature A2 remains out of circuit. Positions 72, 8, S, 9, and 9a are temporary positions, preparatory to position 10. In position 10 the engagement of the brush 10 with the contact 021 divides the current after it has passed in series through the two fields, one part passing by the brush S through A to ground and the other part passing by brush 10 through A2 to ground. The two elds are therefore connected in series with the two armatures in parallel. In passing from position 10 the brush 8 leaves the contact 018, thereby cutting the first armature out of circuit. This gives the momentary condition shown at 10a. Vhen position 11 is reached, the brush 6 bridges onto the contact c6 of the first group, and thereby short-circuits F", the other connections remaining as at position 10. Passing from position 11 the brushes 6 and 7 leave the contacts cs c2, and thereby break the connection between F' F2, and the entire current passes through F2 A2, as shown in position 11% Positions 10, 11, and 11 are preliminary to making the final connections shown in position 12. In this position brushes 1, 5, 6, 7, 8, 9, 10, and 11 are respectively engaged with the contacts c c5 c* c cl2 019 C21 024. The current divides at the brushes 5 and 6, one part passing by conductor C5, brush 18, contacts Z5'Z7, brush 20, field F', brush 19, contacts Z6 Z8, brush 2l, conductor C6, brush 7, contacts 011 012,brush S, armature A., and brush 11 to ground, and the other part passing by conductor C2, contacts Z Z3, brush 1G, eld F2, brush 14, contacts Z2 Z4, brush 17, conductorv C4, brush 9, contacts 019 021, brush 10, and armature A2 to ground, the two motors as a whole being in parallel.

It will be observed, therefore, from the foregoing and from an analysis of Fig. 3 that starting with the motors connected in series with each otherand with artificial resistance I gradually cut out the resistance as the counter electromotive force increases, removing it entirely when the motor speed and the developed counter electromotive force becomes sufficiently high to permit the motors to be connected directly to the circuit. I next by a series of subordinate changes of temporary character decrease the resistance of the before making the next runnin'g position, Y

wherein the two fields are in series with the two armatures in parallel. (Position No. 10.) This position results in a further considerable acceleration of speed, but controlled by the series connection of the fields. Ithen again effect further subordinate changes, in which one armature and one eld are successively cut out preparatory to passing to the final position, in which the two motors as a whole are connected in multiple.

The temporary or passover positions above described I prefer to employ in passing from one to another of the comparatively-perma nent positions; but they may be omitted, as will appear from the description hereinafter given of the modified controller shown in Fig. 2. The other or comparatively-permanent conditions are known as running positions-that is to say, they are conditions which afford successive regulating steps and 'may be maintained so long as it is desired to proceed at the rate of speed which they severally give. It will also be observed that each particular group of contacts has its particu- IOO lar function to perform and although interrelated with adjacent groups is to some extent an independent switch. Group No. 1 forms one terminal of the motor-circuit. It also controls the resistance and operates as a fieldparalleling and shunt switch. Group No. 2 operates to connect the two fields in series. Group No. 3 controls the connections of armature A'. Group No. et controls the connection between the field and armature of the motor A2 F2. Group No. 5 controls the series connection of the two motors as a whole. Contact C24 operates as a grounding-switch for the armature A'.

In the modification shown in Fig. 2 the connections are the same as in Fig. 1 and the general construction of thecontroller is also the same. The arrangementand area of the contacts are, however, somewhat modified. In place of the single extended contacts c c5 of the first group I provide shorter separated contacts c:L cb cf c and ce cf cg c, respectively. Contacts c6 c7 es e9 013 016018 020 o23 024 are made shorter, and instead of the long contacts 019 021 shorter separated contacts ci cj and c c1 are ernployed. In place of the long contacts G22 two shorter separated contacts cm c are provided. The connections remain the same as in Fig. 1. The effect of these changes, as will read- IIS .fr ezial ily appear without tracing ont the several positions in detail, is to eliminate positions 5, 5, 6, 6% 7, 8, 8a, 9, 9, 10, 1l, and lla, leaving positions l, 2, 3, 4, 7, 10, and l2 the same as with the controller shown in Fig. 1.

In other words, after cutting out the external i resistance the two fields are first connected' l l them in series, then connecting their fields 1n in parallel, their series connection is then restored,and the two armatures are connected 'l in parallel, and, lastly, the two motors as a whole are connected in parallel. These, in fact, are the essential positions involved in the operation of the controller shown in Fig. l, the intermediate steps there shown being for the purpose of preventing quite as abrupt changes and obtaining a more gradual acceleration of speed. In lieu of these changes in the controller shown in Fig. 2 the circuit through the controller and the lnotors is momentarily broken in passing from one posi'- tion to the next.

I do not claim herein broadly a method or means of controlling or accelerating a plurality of motors which involves in passing from series to parallel relation and intermediate relation in which an element of one motor is first connected in multiple into a corresponding element of the other motor or motors, as I believe that to be the invention of W. R. I-Iamlen, of Johnstown, Pennsylvania. I do not, however, desire to be limited to irnmaterial details not essential to the scope of my invention as set forth in the appended claims.

The means herein described for carrying into effect my novel method of control form the subject-matter of a separate application to be filed.

IIaving thus described my invention, what I claim as new, and desireto protect by Letters Patent, is-

l. The method of accelerating a plurality of electric motors, which consists in shifting them from series to parallel relation by first connect-ing one element of each in multiple with the corresponding element of the other or others with the remaining elements in series, and then reversing such relation loycircuitchanges wherein the multiple-connected elements are coupled in series and the seriesconnected elements are coupled in parallel, and finally coupling the two motors as awhole in parallel.

2. The method of accelerating a plurality of electric motors,which consists in starting with the motors connected in series, then connecting the fields in parallel with the armatures in series, then reversing this relation by connecting the fields in series with the armatures in parallel, and finally connecting the motors as a whole-in parallel.

3. The method of' accelerating a plurality of electric motors, which consists in starting them in series, then cutting out one motor, and subsequently again connecting it in circuit with its field in parallel with that of the other motor, and its armature in serieswith that of the other motor, then reversing thisI relation by circuit changes whereby the' two fields are connected in series with the two armatures in parallel, and finally connecting the two motors as a whole in parallel.

4t. The method of accelerating a plurality of electric motors, which consists in starting parallel with their armatures in series, then successively cutting out the elements of one motor, and reconnectingv them in circuit with the two fields in series and the armatures in parallel, then again successively cutting out the elements of one motor, and finally connecting the two motors asa whole in parallel.V

5. The method of acceleratin ga plurality of electric motors, which consists in starting them in series, then cutting out one motor, and reconnecting itsY elements in circuit with the other motor with the two fields in multiple and thetwoarm'atures in series, then again cutting out one motor, and subsequently reconnecting its elements in series with the other motor with 'the two fields in series and the two armatures in parallel, then again cutting out one motor, and finally connecting the two motors as a whole in parallel.

6. The method of shifting two motors from series to parallel, which consists in short-circuiting and then cutting out one motor, then connecting in its armature in series with the armature of the other motor, and its fieldwindings in parallel with those ot' the other motor, then again gradually cutting out one motor, and subsequently again connecting it in circuit with the other motor with the two fields in series and' their armatures in multiple, then again gradually cutting out one motor and finally again connecting it in circuit with the two motors as a whole in parallel.

7. The method of acceleratingaplurality of electric motors, which consists in starting them in series with each other and with eX- ternal resistance, gradually cutting out said resistance, then effecting circuit changes by which one element is connected in parallel with the corresponding element of the other motor or motors, with the other elements in series then reversing this relation by effecting circuit changes to couple the series-connected elements in parallel and the parallelconnected elements in series and finally connecting the two motors as a whole in parallel. 8. The method of acceleratingapairof electric motors which consists in starting them in series with each other and with artificial resistance, then gradually cutting out the resistance, then effecting circuit changes to connect the two fields in parallel with the two armatures in series, then effecting further IIC changes to connect the two fields in series I which the fields are connected in parallel and the armatures in series, then reversing the relation by changes which connect the fields in series and the armatures in parallel, and iinally connecting the two motors as a Whole in parallel,V one motor intermediate of each of said changes being momentarily cut out of circuit.

10. The method of accelerating a pair of electric motors, which consists in starting them all in series, then cutting out one motor and reconnecting its elements in circuit with the field-coils of the tWo motors in parallel and their armatures in series With each other and 

